东海PN断面黑潮区域声传播数值模拟

利用BELLHOP声学模式模拟东海PN断面黑湖区域的声传播，比较夏季和冬季的接收信号。冬季的声速小于夏季的声速，但是信号到达时间小于夏季的到达时间，分析表明冬季的声速梯度小于夏季声速梯度，声线的海面反射次和海底反射次数小于夏季，声线的路程短，声线路程对到达时间的影响超过声速的影响，于是冬季信号早于夏季到达。     

A two-point method for estimating wave reflection over a sloping beach

This work presents a frequency-domain method for estimating incident and reflected waves when normally incident waves’ propagating over a sloping beach in a wave flume is considered. Linear wave shoaling is applied to determine changes of the wave amplitude and phase due to variations of the bathymetry. The wave reflection coefficient is estimated using wave heights measured at two fixed wave gauges with a distance. The present model demonstrates a high capacity of estimating reflection and shoaling coefficients from synthetic wave-amplitude data. Sensitivity tests for the present model due to measurement errors of wave amplitudes and distance of two probes can more accurately predict the reflection coefficients. The measurement error of wave amplitude affects more significantly than measurement error of distance of two probes on calculating reflection coefficient of waves over a sloping bed.     

柴西南地区古近系-新近系井-震统一层序地层格架的建立

柴西南地区古近系—新近系是柴达木盆地最主要的油气勘探区和开发区,通过对５４口钻井和录井资料的详细层序地层学的研究,对研究区古近系－新近系的干柴沟组—狮子沟组地层中识别出了一个初次湖泛面和六个最大湖泛面,将其划分为６个三级层序和１７个准层序组,并对十条连井剖面进行了层序对比。在此基础上,对柴西南三维地震区切出了与前述的钻井连井剖面相同的连井地震剖面,并通过对地震剖面层序界限识别和划分,以及将钻井剖 面上的层序划分结果投影到连井地震剖面中等方法,对钻井剖面和地震剖面的层序划分结果进行了对比和调整,使两者完全统一,建立了柴西南区古近系－新近系井—震统一的高精度层序地层格架,这为该区开展岩性油气藏勘探奠定了基础。     

反射波法在人工挖孔桩桩端持力层岩土性状分析中应用探讨

通过某工程人工挖孔桩低应变反射波法实测结果与钻芯法检测结果对比分析,认为低应变反射波法检测结果可定性判断人工挖孔灌注桩桩端持力层岩土性状,岩体的纵波速度与岩石的完整程度、岩石风化程度等因素关系密切~([1~2]),本文利用低应变反射波法检测结果计算了人工挖孔灌注桩持力层纵波速度,利用计算的持力层纵波速度对人工挖孔桩持力层岩土性状进行了探讨。     

银川盆地构造发展——深地震反射剖面揭示浅部地质与深部构造的联系

横跨银川盆地北西西向的深地震反射剖面,清晰揭示了银川盆地边界断裂以及整个地壳的结构构造特征,这对研究具活动大陆裂谷性质的银川盆地浅-深构造关系具有重大的意义。贺兰山东麓山前断裂、黄河断裂作为银川盆地的西、东边界断裂,前者为一条缓倾斜、延伸至上、下地壳边界的犁式断裂,而后者则为一条切穿地壳并延伸进入上地幔的深大断裂。根据深地震反射剖面揭示的地壳结构特征,银川盆地浅部结构并非前人认为的"堑中堑"结构,而是表现为由一系列东倾犁式正断层控制的新生代断陷。略微下凹的Moho面几何形态以及厚2~3.2 km的层状强反射带为下地壳最显著的反射特征。Moho面深度与强反射带厚度变化趋势与银川盆地沉积厚度变化趋势几乎一致。本文认为,强反射带的成因可能是由源自地幔的基性岩浆以岩席状的形式底侵进入地壳底部造成的,而这部分形成强反射带的物质可能补偿了因银川盆地断陷而造成的地壳减薄,最终导致银川盆地之下Moho面并未像之前所认为的那样隆起。     

Subsurface geological-geotechnical modelling to sustain underground civil planning

The aim of the paper was to document the use of 3D subsurface geological-geotechnical modelling to optimise the planning and development of subsurface structures in city areas. The proposed procedure was applied to the analysis of the subsoil of the City of Turin (Northern Italy). The results of more than 300 boreholes were analysed to develop a model of the geological setting up to a depth of 60 m from the surface. The cementation variability of the alluvial sediments was also spatially described and the influence of this aspect on the soil excavation resistance was highlighted. In order to face the need of archiving, correlating and analysing a large amount of data, a 3D GIS (Geographical Information System) was used to better manage the model and to achieve a useful methodological reference that would be available for the planning and construction of future underground works.

A portion of the geological model, related to the centre of the city of Turin (Italy), was chosen to set up a more detailed geotechnical model, based on laboratory tests and back-analysis procedures, as data input for some engineering applications.

Two case studies were performed concerning:

– analyses used to forecast the subsidence induced on the ground surface by the excavation of the metro line;

– the influence of the works of the metro line on the new Underground Railway Link (interference between two important underground works).

A comparison between the forecasts of the degree of cementation, supplied by the 3D model along a metro tunnel tract, and the excavation specific energy effectively absorbed by the head of the boring machine is reported to testify the reliability of the model of the subsoil of Turin centre. This comparison shows the good reliability of the model and its potential to choose of the optimal boring machines for the future development of the Underground Metro System in Turin.     

秦岭陆内造山带岩石圈结构

重新处理和解释叶县—南漳反射地震剖面,并综合利用油气勘探地震剖面,地震层析、大地电磁测深、地热流、气体测量等地球物理和地球化学数据,得到秦岭造山带岩石圈构造模型。识别出秦岭地壳不同时代的重要构造:(1)加里东期华北克拉通向秦岭微板块的俯冲,并造成中上地壳内华北地壳和北秦岭地壳形成锯齿状楔入构造。(2)印支—燕山期扬子克拉通与秦岭微陆块的对冲走滑软碰撞,形成了以南阳地区为中心由一系列规模宏大的逆冲断层组成的负花状构造。(3)白垩纪后,由正副片麻岩交互成层的结晶基底形成的穹隆。(4)盖在结晶基底上的近透明浅变质元古宙地层形成的褶皱基底。白垩纪后,秦岭地区和中国东部其他地区一样,岩石圈地幔遭受到软流圈上升形成蘑菇云构造,岩石圈活化,严重影响构造演化过程。     

两种BRDF室外测量方法的RGM模拟对比与误差分析

目标物的反射特性,无论是在遥感模型还是在遥感反演中都扮演着重要的角色,因此选用正确的自然条件下目标物反射特性的测量方法是遥感定量分析的基础.长期以来在自然条件下(即太阳直射光和天空漫射光同时存在)测量目标物的反射特性时,可以获得BRF(Bidirectional Reflectance Factor)作为目标反射特性的描述,但这样获得的BRF与辐射环境有关.为了消除辐射环境的影响,获得真正能够反映目标物的反射特性的BRDF(Bidirectional Reflectance.Distribution Function),前人提出了一些野外测量的方法.本文在此基础上,利用计算机模拟的辐射度(Radiosity)模型在真实场景基础上模拟BRF值,分析测量方法中存在的系统误差受观测条件影响的大小,比较了测量方法的优劣,提出了野外测量时选择测量方法的基本原则.     

旋挖钻孔灌注桩低应变检测与分析

本文以水阳江特大桥的旋挖钻孔灌注桩低应变检测为例,分析了桩头浮浆及桩身扩径对低应变检测曲线的影响。桩头浮浆可以产生多次反射波或使波形畸变。桩身扩径产生扩径上界面的反相反射波和下界面的同相反射波;桩身扩径很大时,无桩底反射波及扩径下界面反射波,只有扩径上界面的多次反射波。     

The Baza Fault: a major active extensional fault in the central Betic Cordillera (south Spain)

In the Guadix-Baza Basin (Betic Cordillera) lies the Baza Fault, a structure that will be described for the first time in this paper. Eight gravity profiles and a seismic reflection profile, coupled with surface studies, indicate the existence of a NE-dipping normal fault with a variable strike with N-S and NW-SE segments. This 37-km long fault divides the basin into two sectors: Guadix to the West and Baza to the East. Since the Late Miocene, the activity of this fault has created a half-graben in its hanging wall. The seismic reflection profile shows that the fill of this 2,000–3,000 m thick asymmetric basin is syntectonic. The fault has associated seismicity, the most important of which is the 1531 Baza earthquake. Since the Late Tortonian to the present, i.e. over approximately the last 8 million years, extension rates obtained vary between 0.12 and 0.33 mm/year for the Baza Fault, being one of the major active normal faults to accommodate the current ENE–WSW extension produced in the central Betic Cordillera. The existence of this fault and other normal faults in the central Betic Cordillera enhanced the extension in the upper crust from the Late Miocene to the present in this regional compressive setting.